Multiple draft and pressure gage



F. G. PHILU.

MULTIPLE DRAFT AND PRESSURE GAGE.

APPLICATION FILED MAY 31, 1919.

Patented May 25, 1920.

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2 SHEETS-SHEET I.

a w ru m 1 a F n w a a a m f INVENTOR Paw/4% 6;. 7 mm BY WW ATTORNEYS F. G. PHILO.

MULTIPLE DRAFT AND PRESSURE GAGE.

APPLICATION FILED MAY 31,.1919.

Patented May 25,1920.

2 SHEETSSHEET 2.

INVENTOR (-7 F'H/ A0 TR Pam/K TONEYs UNITED FRANK G. PHILO, OF ELMI-IUBST, NEW YORK.

MULTIPLE DRAFT AND PRESSURE GAGE.

Application filed May 31, 1919.

invented certain new and useful Improvements in Multiple Draft and Pressure Gages, of which the following is a specification.

My invention relates to multiple draft and pressure gages, and particularly to a gage for indicating pressure conditions at various points in the draft system of a furnace of forced draft type. The particular object of my invention is to provide an instrument which graphically portrays the draft conditions and thus guides the engineer in the proper regulation on the draft at the several indicated points in the system to secure the most advantageous operation of the furnace under varying fuel conditions and with various depths of fire bed.

In the accompanying drawings Figure 1 is a more or less diagrammatic elevation of a furnace installation showing my improved gage applied thereto;

Fig. 2 is a side elevation of the gage alone;

Fig. 3 is a front elevation of the gage drawn to a larger scale;

Fig. 1 is a vertical section therethrough on the line 4-4 of Fig. 8; and

Fig. 5 is a cross section on the line 5-5 of Fig. 3.

It is a matter of great importance for the efficient operation of large furnaces working under forced draft, that.the pressure of the blast at different portions of the fuel bed be varied to insure proper combustion at these various points. While the value of such regulation has been recognized and means provided for regulating the blast at different areas of the fuel bed, the actual regulation has been dependent upon observation of the fuel bed itself, and of a rather hit or miss character without accurate scientific indication of blast conditions or of the proper relation between pressures at various fire bed areas. The present gage is designed not only to indicate graphically the pressure conditions at various points in the blast system, but to instruct and guide the engineer as to the proper relative pressures Specification of Letters Patent.

Patented May 25,1920.

Serial No. 301,067.

pt the different indicated points in the sys- In the form shown the furnace comprises a traveling grate 10, to which the fuel is fed from a hopper 11, forming a fire bed 12, and discharging its ash to the pit 13 at the opposite end of the grate. Beneath the grate a Wind box 14 is arranged to which the fan 15 delivers a forced draft through the air duct 16. The Wind box 14: is subdivided into several chambers 17, 18, 19 and 20 by the twyer boxes 21, 22 and 23, which communicate with the air duct 16. Usual means (not shown) are provided for regulating the amount of air admitted to the several chambers 17 to 20 from the respective twyer boxes. Above the fuel bed 12 is the combustion chamber 24, from which the products of combustion pass through the boiler pipes 25 to the stack 26, in which is arranged the damper 27. The regulation of the blast in the several chambers is dependent upon several factors, such for example, as the nature of the fuel, the depth of the fuel bed, and the rate of travel of the grate, etc. The fuel bed has, in any event, an initial depth adjacent the hopper greater than its depth at the discharge end of the grate where the fuel is practically burned out. Obviously a much lower pressure is re quired for the draft at the dischargeend of the furnace than is necessary at the hopper end. Again, while the proportional pressures should remain substantially the same, the actual pressures will be considerably greater if the depth of the fuel bed is increased. Under all conditions, however, the pressure in the blast chamber 17 will be greater than the pressure in the chamber 18, and similarly the pressure in 18 will be greater than the pressure in 19 or 20. Since the ratio of pressures which gives the best practical results from the fire can be accurately determined, this ratio should be accurately maintained in the several chambers.

It is also desirable to know the pressure in the combustion chamber 21, since obviously if the pressure in the combustion chamber is below atmosphere a suction effort will be added to the pressure in the blast chambers, whereas if a pressure above atmosphere exists in the combustion chamber the effective pressures in the blast compartments is diminished. It is desirable that the pressure in the combustion chamber be maintained substantially at atmosphere, or only slightly below, in order to prevent leakage of cold air into the furnace chamber through the hopper or the various furnace joints. Again, it is desirable to know the pressure in the stack below the damper 27, thus gaging the impedance of the boiler tubes'to the flow of the combustion gases therethrough. The available pressure in the air duct at the point of admission to the several twyer boxes should also be indi cated. These are the principal points at which the pressure in the draft system should be known in order to effect the proper regulation of the blast.

As here shown the present gage comprises a hollow casting 28 forming a reservoir 29. A series of gage glasses, here shown as six in number, viz. 30, 31, 32, 33, 3 1 and 35, are arranged in front of the reservoir and supported upon a projecting ledge 36. A corresponding series of holes 37, bored through the ledge 36, establish communication between the reservoir and each of the gage glasses separately. A series of screw nipples 38, 39, d0, A1, 42 and "13 mounted in the head 44: of the casting communicate with the several gage glasses and afford means for connecting the latter to the respective points at which pressure measurement is desired. In the top of the reservoir a vent plug 15 is provided for maintaining the rese'rvoir at atmospheric pressure, or the plug is substituted by a nipple 46 by which communication may be established between the reservoir and any point in the draft system. The fluid employed in the reservoir is preferably a non-volatile heavy oil colored to sharply define its level in the gage glasses. Between the gage glasses and the reservoir T mount a chart 4E7 calibrated to show various degrees of pressure, and preferably comprising for certain of the gage tubes (here shown as tubes 33, 34, 35) a group of stepped calibration lines 48, 49, 50 and 51 to indicate the proper ratio of pressures in corresponding blast chambers, under different conditions of fuel or different depths of fuel bed. I have shown the gage glass 35 connected to the blast chamber 17; the gage glass ea connected to the blast chamber 18; and the gage glass 33 connected to the blast chamber 19. As indicated by the calibration lines 4851 of the chart, the pressure in chamber 17 should always be greater than that in the chamber 18, while that in the chamber 19 should be still lower; the ratio between the pressures being accurately predetermined to secure the best results under different conditions. The pressure in the combustion chamber 24: is indicated by gage glass 32, to

which it is connected, and as therein shown the pressure is slightly below atmosphere. If preferred the connection from the combustion chamber may be led to the reservoir 29, thus enabling the engineer to determine the efiective pressure of the blast by adding to the readings of the gage glasses 33, 34 and 35 the minus reading of the glass 32.

The stack pressure is indicated by the gage glass 31, to which it is connected, and as shown in Fig. 1 this pressure should be considerably below atmosphere. The total available pressure in the air duct at the twyer boxes is indicated by the gage glass 30.

l/Vhile the number of gage tube glasses may be varied, 1 have found that a group of six is sufficient for the average furnace to enable the engineer to properly control the draft. The connection of the several gage glasses to the common reservoir, while resulting in a certain variance in the. liquid level in the reservoir, does not cause any appreciable rise or fall therein, or materially affect the accuracy of the readings of the glasses. It insures, moreover, that in case of any leakage or evaporation, the relative loss is the same for all the gage glasses, and the relative positions of the indicating liquid therein will be maintained even if the levels are not constant. The chance of loss by evaporation or leakage is minimized,

reservoir and a plurality of gage glasses communicating with said reservoir, together with means for connecting said gage glasses independently with different sources of pressure to be measured.

2. A multiple gage comprising a liquid reservoir and a plurality of gage glasses communicating with said reservoir, together with means for connecting said gage glasses independently with different sources of pressure to be measured, and means for connecting said reservoir either with the air or with a source of pressure.

3. A multiple gage comprising a liquid reservoir, a plurality of associated gage glasses communicating therewith, and a chart associated with said glasses and having a ratio calibration for certain of said gage glasses and means for connecting said gage glasses independently with different sources of pressure to be measured adjacent glasses with a pressure pipe, and means for the ratio calibrated portion of the chart. establishing communication between the res- 4. A multiple gage comprising a reservoir, ervoir and either atmosphere or a pressure 10 a ledge projecting therefrom, a series of pipe at will. 5 gage glasses supported on said ledge and In testimony whereof I have signed my separately communicating with the resername to this specification. voir, means for connecting each of said FRANK Gr. PHILO. 

